<template>
  <div class="pagination">
    <button :disabled="pageNo==1" @click="$emit('getPageNo',pageNo-1)">上一页</button>
    <button v-if="startNumAndEndNum.start>1" @click="$emit('getPageNo',1)"   :class="{active:pageNo==1}">1</button>
    <button v-if="startNumAndEndNum.start > 2"> ···</button>

    <!-- //中间部分 -->
    <button v-for="(page,index) in startNumAndEndNum.end" :key="index" v-if="page>=startNumAndEndNum.start" @click="$emit('getPageNo',page)" 
    :class="{active:pageNo==page}">{{page}}</button>

    <button v-if="startNumAndEndNum.end <totalPage -1">···</button>
    <button v-if="startNumAndEndNum.end < totalPage" @click="$emit('getPageNo',totalPage)" :class="{active:pageNo==totalPage}">{{totalPage}}</button>
    <button :disabled="pageNo==totalPage" @click="$emit('getPageNo',pageNo+1)">下一页</button>

    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props:['pageNo',"pageSize","total","continues"],
  
  computed:{
    totalPage(){
        return Math.ceil(this.total/this.pageSize);
    },
    startNumAndEndNum(){
        const{ continues,pageNo,totalPage} = this
        let start = 0, end = 0;
        if(continues >totalPage){
            start = 1;
            end = totalPage;
        }else{
            start = pageNo - parseInt(continues/2);
            end = pageNo + parseInt(continues/2);

            if(start <1) {
                start = 1;
                end = continues;
            }
            if(end >totalPage){
                end = totalPage;
                start =totalPage - continues + 1;
            }
        }
        return {start ,end}
    }
  }
};
</script>

<style lang="less" scoped>
.pagination {
    text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
.active{
    background-color: skyblue;
}
</style>
